Sold-phase extraction is now widely used for preconcentration and cleanup of analytical samples, for purification of various chemicals, and for large-scale applications such as removal of toxic or valuable substances from a variety of predominately aqueous solutions. Typical applications include methods for determination of trace amounts of pesticides, for determination of trace organic contaminants in water, for analysis of industrial waste water, determination of azaarenes in water, evaluation of porous polymers, isolation of organic compounds from ground water, sampling of priority pollutants in waste water, collection and concentration of environmental samples, and for pretreatment of urine samples.
For analytical purposes, solid phase extraction is usually performed using a small column or cartridge containing an appropriate resin. However, membranes loaded with appropriate resins have also been used for solid phase extraction. Following uptake of extractable solutes from a predominantly aqueous sample, it is common practice to elute the adsorbed materials from the resin by a small amount of an organic solvent such as ethyl acetate.
Chemically-bonded silica, usually with a C.sub.18 or C.sub.8 organic group, is by far the most commonly used material for solid phase extraction. Minor use has been made of porous polystyrene or other polymeric resins in solid phase extraction. However, these materials have several shortcomings for use in solid phase extraction. First, they are hydrophobic and therefore do not make good surface contact with predominately aqueous solutions. Secondly, pretreatment of the solid phase extraction materials with an activating solvent (such as methanol, acetone, or acetonitrile) must be used to obtain better surface contact with the aqueous solution being extracted; and, the activating solvent can be gradually leached out of the resin, thereby causing the extraction to become ineffective. This is particularly true if the solid phase extraction column inadvertently goes dry, causing air to be sucked into the column. Third, many types of organic compounds are incompletely extracted from predominately aqueous solutions. This is especially true with chemically-bonded silica resins.
In sum, it can be seen that the usual solid phase extraction adsorbent resin, that is chemically-bonded silica, often with the C.sub.18 or C.sub.8 organic group, has serious drawbacks. There is, therefore, a continuing need for a new type of chemically derivatized resin which overcomes the deficiencies of chemically-bonded silica, particularly for use with removal of polar organic solutes. The primary objective of the present invention is to fulfill this need.
The method and means of accomplishing the primary objective, as well as others will become apparent from the detailed description of the invention will follows hereinafter.